unable to delete a node in double linked list

[Jeevan83]

I am trying this without a head/start pointer which would generally hold the address of first node. I have 3 nodes here from which I am trying to delete last node, but its not happening. I might be wrong in my logic and this is my first linked list program, so please help me!

#include <stdio.h>
#include <stdlib.h>
 
struct dll{
            struct dll *prev;
            int data;
            struct dll *next;
          };
 
int main()
{
    struct dll *p1,*p2,*p3, *temp;
    p1=malloc(sizeof(struct dll));
    p2=malloc(sizeof(struct dll));
    p3=malloc(sizeof(struct dll));
    temp=malloc(sizeof(struct dll));
    p1->prev=NULL;
    p1->data=1;
    p1->next=p2;
    p2->prev=p1;
    p2->data=2;
    p2->next=p3;
    p3->prev=p2;
    p3->data=3;
    p3->next=NULL;  
    struct dll *add=NULL;
    int count=0;
    printf("add of p1::%p add of p2::%p add of p3::%p add of p1->prev::%p add of p1->next::%p add of p2->prev::%p add of p2->next::%p add of p3->prev::%p add of p3->next::%p\n",p1,p2,p3,p1->prev,p1->next,p2->prev,p2->next,p3->prev,p3->next);
    while(p1->next!=NULL)
    {
        count++;
        p1=p1->next;
    }
    printf("no of nodes %d\n",count+1);
    puts("enter the addresss of node to delete it");
    scanf("%p",&add);
    while(p1->next!=NULL)
    {
        if(p1->next==add)
        {
            temp = p1->next;
            p1->next=NULL;
            free(temp);
            temp=NULL;
        }
        else
        p1=p1->next;
    }
    puts("after deletion attempted");
printf("add of p1::%p add of p2::%p add of p3::%p add of p1->prev::%p add of p1->next::%p add of p2->prev::%p add of p2->next::%p add of p3->prev::%p add of p3->next::%p\n",p1,p2,p3,p1->prev,p1->next,p2->prev,p2->next,p3->prev,p3->next);
 
    while(p1->next!=NULL)
    {
        count++;
        p1=p1->next;
    }
    printf("no of nodes %d\n",count+1);
    free(p1);
    p1=NULL;
    free(p2);
    p2=NULL;
    free(p3);
    p3=NULL;
return 0;
} 

output::::

add of p1::0x9605008 add of p2::0x9605018 add of p3::0x9605028 add of p1->prev::(nil) add of p1->next::0x9605018 add of p2->prev::0x9605008 add of p2->next::0x9605028 add of p3->prev::0x9605018 add of p3->next::(nil)

no of nodes 3

enter the addresss of node to delete it
0x9605028

after deletion attempted

add of p1::0x9605028 add of p2::0x9605018 add of p3::0x9605028 add of p1->prev::0x9605018 add of p1->next::(nil) add of p2->prev::0x9605008 add of p2->next::0x9605028 add of p3->prev::0x9605018 add of p3->next::(nil)

no of nodes 3

In this example i am trying to delete the node 3 which is p3, by deleting its address 0x9605028. But after deletion the node count is still 3 and addresses are like unexpected!

[weaknessforcats]

Using a double linked list, one with next/prev pointers, should allow you to delete any node.

Assume p1 is a pointer to the last node. That is, p1->next is 0.

To delete this node, set p1->prev->next to p1->next, free the p1 members and then free p1.

To delete a node in the middle of the list, let's call it cur for the current node, you must:
1) set cur->prev->next to cur->next
2) set cur->next->prev to cur->prev->next

The cur node is now out of the list. free the members ansd then free the node.